Copying of material is well known and many diverse systems and/or methods have heretofore been suggested and/or utilized to achieve the desired end. One such system is an electrical-signal-driven printer wherein signals representative of the visual images on each page to be printed are supplied to the printer in numerical page order. If only one side of a recording medium (such as a paper copy sheet, for example) is to have an image printed thereon, each signal may be used when received to print the visual image on sheets as fed through the printer. When multiple copies are desired, however, the electrical signals must be inserted, when received, in some form of a recirculating delay line and the delay line recycled as needed to print the number of copies desired.
For simplex copies (i.e., copies having an image on one side only), each electrical signal representative of a page to be imaged is brought to a copying, or printing, area where the image is formed on the sheet and the sheet then discharged from the printer.
For duplex copies, i.e., copies having an image on both sides of the copy sheet, different electrical signals representative of each page must be brought at different times to the printing area and the copy sheet must be brought to the printing area with one side exposed for printing during a first pass and the opposite side exposed for printing during a subsequent second pass. Obviously, this becomes complicated since it is often desired that each page of the sequence appear in order so that each even numbered page appears on the back side of each odd numbered page, as in a book, for example. In addition, further complications are introduced when multiple copies of each page are to be printed.
An example of a system and method for effecting printing of copies by sets is shown in U.S. Pat. No. 4,099,254. While the device shown in this patent solves many of the problems heretofore associated with copy generation, it does not provide for job recovery, i.e., recovery from jams occurring with respect to copy sheets, or errors introduced due to double, or lack of, feed of copy sheets.
Job recovery has been heretofore suggested and/or utilized with respect to copying devices, including those capable of printing multiple copies and/or effecting duplex copying. Such job recovery, however, has not been completely satisfactory, at least for all instances, and particularly with respect to recovery from jams occurring during second side copying of multiple duplex copies.
Prior art suggestions have included devices with counters and the like for counting documents and/or copy sheets to effect both simplex and duplex copying. However, such devices have not proven to be completely satisfactory and/or capable for use in job recovery for automatic recovery from jams occurring with respect to generation of multiple copies and/or jam recovery during second side copying.
In addition, heretofore known copying devices and/or methods have not proven to be completely satisfactory for generation of complete sets of copies when double or lack of copy sheet feeding has occurred, or when interruption of copying has occurred. In addition, while providing for copy counts, such devices and/or methods have not adequately provided for counts of copies generated without including in such counts any copies generated for replacement purposes.